Parallel harmony moves a chord shape as a block instead of treating every voice as an independent line. It can sound polished and cinematic, but it does not create the same kind of voice leading as functional harmony.
In diatonic parallel motion, each chord stays inside the key, so its quality may change. In chromatic planing, the same interval shape slides intact, even when that introduces notes outside the key.
Compare the two approaches
C major to D major keeps the major-triad shape. A diatonic move from C to D in C major would instead give C major to D minor.
Try it
- Choose a chord quality and a short root path.
- Move the full shape by the same interval each time.
- Make a second version that stays diatonic, then compare the color and direction.
Key takeaway
Parallel motion prioritizes a consistent chord shape. Decide whether you want the key to control chord quality or the shape to remain fixed.